The few times that I haven't gotten that one, I have been a jerk and made them take the one they were giving me out of the box and letting me go over it to make sure there was nothing wrong with the one they gave me from the back.
That's not being a jerk, that's being an educated consumer.
I will not buy a gun, .22 excluded, if I can't dryfire it first. To me that's like buying a car without test driving it.
A few of the models I have bought have been the display model. I am lucky enough that my primary LGS is big enough to usually have a few in the back so I don't typically don't have to worry about it. In a centerfire pistol I am typically not worried about damage from dryfiring. I do make sure to triple check it for any scratches etc that might have resulted from a careless customer. My P30 was a display model that had been sitting there for 6 months. I haven't encountered any issues that I could trace to that.